From bb10325339898d2833a9f24e9e0252b2c257beb1 Mon Sep 17 00:00:00 2001
From: Nico Weber <nicolasweber@gmx.de>
Date: Mon, 29 Apr 2013 08:57:31 -0700
Subject: Introduce a Truncate() function that works on POSIX and Windows.

Hopefully fixes the build on Windows.
---
 src/build_log_test.cc | 10 +---------
 src/deps_log.cc       |  4 +---
 src/deps_log_test.cc  |  4 ++--
 src/util.cc           | 20 ++++++++++++++++++++
 src/util.h            |  3 +++
 5 files changed, 27 insertions(+), 14 deletions(-)

diff --git a/src/build_log_test.cc b/src/build_log_test.cc
index 2dd6500..4639bc9 100644
--- a/src/build_log_test.cc
+++ b/src/build_log_test.cc
@@ -143,15 +143,7 @@ TEST_F(BuildLogTest, Truncate) {
     log2.RecordCommand(state_.edges_[1], 20, 25);
     log2.Close();
 
-#ifndef _WIN32
-    ASSERT_EQ(0, truncate(kTestFilename, size));
-#else
-    int fh;
-    fh = _sopen(kTestFilename, _O_RDWR | _O_CREAT, _SH_DENYNO,
-                _S_IREAD | _S_IWRITE);
-    ASSERT_EQ(0, _chsize(fh, size));
-    _close(fh);
-#endif
+    ASSERT_TRUE(Truncate(kTestFilename, size, &err));
 
     BuildLog log3;
     err.clear();
diff --git a/src/deps_log.cc b/src/deps_log.cc
index c52503b..9866540 100644
--- a/src/deps_log.cc
+++ b/src/deps_log.cc
@@ -215,10 +215,8 @@ bool DepsLog::Load(const string& path, State* state, string* err) {
     }
     fclose(f);
 
-    if (truncate(path.c_str(), offset) < 0) {
-      *err = strerror(errno);
+    if (!Truncate(path.c_str(), offset, err))
       return false;
-    }
 
     // The truncate succeeded; we'll just report the load error as a
     // warning because the build can proceed.
diff --git a/src/deps_log_test.cc b/src/deps_log_test.cc
index 9623d17..b3d6b74 100644
--- a/src/deps_log_test.cc
+++ b/src/deps_log_test.cc
@@ -251,11 +251,11 @@ TEST_F(DepsLogTest, Truncated) {
   int node_count = 5;
   int deps_count = 2;
   for (int size = (int)st.st_size; size > 0; --size) {
-    ASSERT_EQ(0, truncate(kTestFilename, size));
+    string err;
+    ASSERT_TRUE(Truncate(kTestFilename, size, &err));
 
     State state;
     DepsLog log;
-    string err;
     EXPECT_TRUE(log.Load(kTestFilename, &state, &err));
     if (!err.empty()) {
       // At some point the log will be so short as to be unparseable.
diff --git a/src/util.cc b/src/util.cc
index 91e8fad..e78dda3 100644
--- a/src/util.cc
+++ b/src/util.cc
@@ -29,6 +29,7 @@
 #include <sys/types.h>
 
 #ifndef _WIN32
+#include <unistd.h>
 #include <sys/time.h>
 #endif
 
@@ -354,3 +355,22 @@ string ElideMiddle(const string& str, size_t width) {
   }
   return result;
 }
+
+bool Truncate(const string& path, size_t size, string* err) {
+#ifdef _WIN32
+  int fh;
+  fh = _sopen(kTestFilename, _O_RDWR | _O_CREAT, _SH_DENYNO,
+              _S_IREAD | _S_IWRITE);
+  int success = _chsize(fh, size);
+  _close(fh);
+#else
+  int success = truncate(path.c_str(), size);
+#endif
+  // Both truncate() and _chsize() return 0 on success and set errno and return
+  // -1 on failure.
+  if (success < 0) {
+    *err = strerror(errno);
+    return false;
+  }
+  return true;
+}
diff --git a/src/util.h b/src/util.h
index 07381a1..9740565 100644
--- a/src/util.h
+++ b/src/util.h
@@ -76,6 +76,9 @@ double GetLoadAverage();
 /// exceeds @a width.
 string ElideMiddle(const string& str, size_t width);
 
+/// Truncates a file to the given size.
+bool Truncate(const string& path, size_t size, string* err);
+
 #ifdef _MSC_VER
 #define snprintf _snprintf
 #define fileno _fileno
-- 
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